Supporters of the Chicago Teachers Union rallied Saturday on the sixth day of a strike that has shut down the city's schools, even as a deal with the school board was in the works.

Both sides expressed optimism that students could be back in school by Monday, but the massive gathering was a reminder that until a deal is signed, the strike is not over.

"We don't have an agreement, we have a framework for an agreement," union President Karen Lewis reiterated at the rally Saturday at Union Park.

Joining the thousands of teachers at the rally were parents and students who declared their solidarity with them.

"I am willing to stand by my teachers' side for as long as it takes," high school student Angela Casa told the crowd, "because through this whole journey, they are keeping their heads up for us."

The union and the city's school board reached a tentative agreement on Friday over a dispute on new contract terms that had closed public schools for 350,000 students.

Union officials were meeting over the weekend to draft specific language for the agreement, Lewis said. They will then present the document to a special committee of union representatives, at which time a majority vote will be taken on whether to suspend the strike.

"Our delegates were not interested in blindly signing off on something they have not seen," Lewis said Friday.

Chicago School Board President David Vitale was similarly positive about moving forward.

"We have in place frameworks around all of the major issues that should allow us to conclude this process and to conclude it in time for our kids to be back in school on Monday morning," he said.

A source close to the negotiations said some of the terms include: keeping the current length of school year and school day; giving principals the freedom to hire their own teachers; and, chief among the dispute's sticking points, updating the teacher evaluation system for the first time in 40 years.

Lewis said Friday afternoon that she was "very comfortable" with the teacher evaluations issue under the proposed framework agreement.

Chicago Mayor Rahm Emanuel praised the progress made between the two sides after days of sometimes contentious meetings.

The union, which represents nearly 30,000 teachers and support staff, called the strike Sunday night.

Saturday, teacher Juanita Martinez said she was ready for it to end.

"This is more work than being in the classroom," she told CNN. "I'd rather be teaching. I miss my students, I miss my neighborhood, I miss my community. ... I'm ready to go back."

The union previously said the two sides had been close to a deal on pay, but far apart on teacher evaluations, benefits and other issues.

Teachers were concerned about job security in the wake of a new program that evaluates them based on their students' standardized test scores. Union board member Jay Rehak called the program "data-driven madness."

As many as 6,000 teachers could lose their jobs under the evaluation system, said Lewis, who had called the system "unacceptable." The mayor's office, the city and school officials have questioned that job-loss figure.

The median base salary for teachers in the Chicago public schools in 2011 was $67,974, according to the system's annual financial report.

Chicago teacher strike

Teacher Xian Barrett writes he knows people are angry at Chicago teachers, but the strikes is about kids, he says. Nobody wants kids in overheated classroms with too few books and more tests than teaching.

The hard-nosed stance taken by Mayor Rahm Emanuel in the Chicago teachers' strike dovetails with the education goals of his former boss, President Barack Obama, but observers disagreed Monday over how well it serves the city's schoolchildren.